Fighting knife



FIG. 1 shows a side view of my design for a fighting knife;

FIG. 2 shows a similar side view thereof;

FIG. 3 shows a bottom and side perspective view thereof;

FIG. 4 shows a rear and opposite side perspective view thereof; and,

FIG. 5 shows the top view thereof. 

The ornamental design for a fighting knife, as shown and described. 